1. Field of the Invention
The present invention relates to a disposable microwave reactive cooking, crisping, and browning food package which produces a thermal heating effect when exposed to microwave energy and which contains gas permeable means to allow venting of gases and vapors which improve browning and crisping of the contained food product.
2. Background Art
The number of microwave ovens in use has grown tremendously in recent years. Associated with this growth in microwave oven usage has been a similar growth in the demand for microwaveable prepared foods. As manufacturers of microwaveable prepared foods seek to introduce new and different kinds of food products, they are often faced with the problem of how to compensate for the difference in results when heating foods in a microwave oven, compared to heating in a conventional oven. Among these problems is the common complaint that food cooked by microwave energy lacks the desired degree of brownness and crispness that foods such as pizzas have when cooked in a conventional oven. With browning and crisping as the objective, numerous specialized microwaveable food packages have been developed. Many such specially developed packages, however, are not adaptable to foods which, during microwave heating, produce grease and vapor which cause the product to become soggy and soft. Furthermore, certain specialized packages which have been designed to overcome some of these problems are expensive and therefore not disposable.
Specialized packages developed and designed to achieve microwave browning of foods contain a reactive film or element which converts microwave energy into thermal energy. The thermal energy produces browning and crisping of an item of food situated adjacent said heating element. In some cases the food is disposed within an outer package body that is used for shipping and storage as well as for heating of the food product. In other cases, the food is disposed on a tray-like member that is situated within an outer package body for shipping and storage, but is removed and rearranged relative to the outer package body when the food item is prepared for heating in a microwave oven.
One type of disposable package that is used for both shipping and storage as well as heating of items of food is represented by Brastad U.S. Pat. No. 4,267,420 and Brastad, et al. U.S. Pat. No. 4,230,924. In these patents, flexible and semi-rigid sheets of microwave interactive materials are wrapped closely about individual items of food so that when the package is exposed to microwave energy, at least a portion of the microwave energy impinging the package will be converted into heat for browning the surface of the food. However, such packages have been found to pose problems with various types of food which give off heat, grease, and/or vapor. Furthermore, irregularly shaped foods are difficult to wrap. As a result, uneven heating, browning, and cooking of the food has been experienced.
Another example of a specialized reactive package is disclosed in U.S. Pat. No. 4,190,757 to Turpin. This patent discloses a carton for microwave heating of pizza including an interactive layer which converts microwave energy to heat for browning the pizza crust and a spacer element for elevating the interactive layer above the bottom wall of the carton. Because of the specialized and complex configuration of the carton assembly, manufacturing and production costs are excessive. Moreover, because this carton has a planar panel of interactive material without a gas permeable aperture for venting, it does not provide an effective means for microwave browning and crisping of foods such as large pizzas having crust diameters in excess of seven (7) inches.
Certain packages utilizing interactive layers require some form of manipulation prior to use or are limited in their uses, such as commonly assigned U.S. Pat. No. 4,553,010 to Bohrer and U.S. Pat. No. 4,555,605 to Brown. The packaging arrangements disclosed in these patents are extremely well suited for the microwave heating of certain types of food, such as popcorn in the case of Bohrer and small diameter pizza in the case of the Brown, but these arrangements do not deal with the problems associated with microwave cooking of certain types of foods, particularly those having large diameter pie crusts. The planar nonporous nature of the reactive support surface on which the food product is placed limits its use to browning and crisping food products which have small planar areas adjacent the reactive heater.